在一组数据中查找局部最大值

Question

我正在写一份物理实验室报告，并使用传感器收集了大量关于摆动摆的角度如何随时间变化的数据。 样本超过 3 分钟，有超过 3000 个数据点。 当绘制在图表上时，它会产生一条正弦曲线，正如它应该的那样。

当我尝试使用 Python 找到最大值时，就会出现问题。 我需要最大值来查看阻尼对钟摆的影响。 当我运行以下代码时，我只得到 29 个最大值，而且我知道有 ~150 个最大值。 如何改进我的代码以获取所有这些？

我的算法检查参考点前后的 4 个点，如果参考点具有最大值，则将其添加到最大值数组中。

请注意，我仍然是 python 的初学者，所以如果您使用任何复杂的语言，很可能 go 在我的脑海中，所以，提前抱歉。

angle = allAngles.readlines()

maxima = [0]

def checker(number):
    counter = 0
    for j in range(-4, 5):
        if float(angle[number + j]) <= float(angle[number]):
            counter += 1
    if counter == 9:
        return True

for i in range(4, len(angle)-6):
     if checker(i):
         if float(angle[i]) != maxima[len(maxima)-1]:
            maxima.append(float(angle[i]))

angleData.txt 包含以下数据：

0
0
0.0349065850399
0.0698131700798
0.10471975512
0.13962634016
0.191986217719
0.244346095279
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0.541052068118
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0.610865238198
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0.663225115758
0.680678408278
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0.698131700798
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0.750491578358
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还有更多，但我受到这篇文章的限制

Answer 1

您的问题在于您的排除逻辑：

     if float(angle[i]) != maxima[len(maxima)-1]:

您的许多连续最大值具有相同的值，但在文件中由大约 25 行分隔。 您上面的检查代码明确排除了这些。

如果您试图保持“平线”最大值不被记录多次，那么您需要检查本地元素，而不是最后一个成功的元素：检查前一个元素。

     if float(angle[i]) != float(angle[i-1]):

程序中还有其他需要清理的东西，但这会产生所需的功能差异。

最值得注意的是，删除连续转换：您的程序仅处理float ，因此将所有内容都隐藏一次：

angle = [float(x) for x in open('qqq').readlines()]

然后，使用内置的max function，而不是自己编写：

 if angle[i] == max(angle[i-4:i+5]):